[R-390] Cosmos PTO, spring-loaded linearizing core?

[JMILLER1706 at cfl.rr.com]

Just to clarify my PTO was clean and shiny on first opening as in the 
photos, although the grease on the main inductor lead screw had 
blackened a bit.  Sounds like somebody at Raytheon got a little heavy 
handed with the grease gun.  Another thing:  I wonder if some coil 
parts have absorbed grease and expanded?  This happens to the material 
of the coil forms - they absorb lubricants, expand and then the slugs 
don't move in them too well any more.  I don't recal what the coil form 
was made of for the linearizing coil, but if it is paper based or 
easily absorbs moisture, it could have expanded around the plunger and 
frozen it in place.

----- Original Message -----
From: Tim Shoppa <tshoppa at wmata.com>
Date: Monday, February 27, 2006 1:27 pm
Subject: RE: [R-390] Cosmos PTO, spring-loaded linearizing core?
To: r-390 at mailman.qth.net

> Bill writes:
> 
> > OK, the ring is not the main spring. I do see the red part with
> > the white dot in Jim's pictures. What I can't see is how to
> > remove the coil assembly, with that long steel base that surely
> > could contain a spring. The picture with "The two halves of the
> > PTO being separated ..." shows what appears to be a wrench flat
> > at the end of the "steel" (or some gray metal) base that is close
> > to the frame. Have you disassembled it that far?
> 
> It's easier than you see.  There are two cheese-head screws (which
> you do not see in Jim's photos) that hold the linearizing core base
> onto the main plate. It's tight but not too hard to get to those
> screws. The material seems to be aluminum for most of the PTO innards
> that are not phenolic/ plastic.
> 
> > If you do have the coil assembly free of the PTO, can you see a
> > way to look in the steel barrel? 
> 
> Yeah, I don't see a spring. I see a threaded hole in the base. The
> thread on the screw attached to the core threads through that
> hole. Current theory is that the threaded hole isn't part of the base
> but is part of a sliding cylinder that goes up and down in the base,
> and that the cylinder has somehow seized up in mine.
> 
> > OTOH, Cosmos didn't machine anything that didn't have to be 
> machined.> Perhaps the red rod is hollow. The inside end pushes 
> against the
> > spring. The outside end pushes against something like a rivet head
> > on the end of the inner rod that attaches to the coil slug.
> 
> That's a good theory, and it may indeed be what's in other Cosmos
> PTO's but that's not what I see in mine.
> 
> I am tempted to tear down my other Cosmos PTO (it is actually in
> much bigger need of linearization) just to see if
> I can slide the core in that one!
> 
> I looked at the Cosmos patent #3,098,989 and while the externals
> of the linearing inductor match mine, the innards of base #28 and
> core #31 do not look like mine.
> 
> That's a really well-written patent BTW. Occasionally for work I have
> to look at more modern patents and they are written like crap in
> comparison.
> 
> Tim.
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